I removed the bench seat and cover to get to the top of the transmission as I thought the source would be the 3 plugs. Used engine degreaser and power washed it down. The 3 plugs had already been sealed. I noticed this was where the leak was coming from. I don't see anything that would connect to it. What is it? Anyone else run into this issue? If so what did you use to seal it? Thanks in advance.

 

On older trucks, the speedo cable connected to the big port. But on '92-only, that was used to send a VSS to the cruise control module. And the big port is blocked by that bottle-cap-looking plastic plug. Apparently, that one has cracked, or someone put something in the trans that degraded the O-ring seals, or... That same part (with the plug) was also used on many FS cars, like the '92-01 Crown Vic/MGM/LTC. So it should be fairly common in JYs if you don't want to buy new. If you DO buy new, I'd only get a MotorCraft, Standard, or other US-made part. I'm not sure what the difference is between Standard SC37 & SC37T (cheaper by half).

I also don't know the difference between Ford E9LZ-9E731-A & MotorCraft DY588, other than maybe the blue anodizing.

On non-cruise trucks, there's just a bore plug driven into the transmission case, but IDK what size or where to get one (if you wanted to delete the sensor & disable cruise).